This project has been in the back of mind for a few years now, and at the end of last summer I pulled the trigger and started to collect all the necessary bits and pieces to build a solid E30 M20B25 turbo. With so much documentation and experience out there it wasnít that difficult to figure out what I wanted and how to get it. I want this write-up to be an overview of the whole project, and Iíll describe what I think are important points. If there are any questions, just ask! This is my first attempt at a turbo, so there were definitely some good learning experiences here for me.

The victim for this undertaking is an í86 325, with an existing M20B25 swap and CatCam 283 (which was installed a few years ago).

Since a major factor with this project is cost, the obvious answer for engine management is a Megasquirt ECU. I decided to go with the MSII with the extra code to have the ďbest-of-the-worstĒ hardware/software to work with. They are pretty straight-forward to assemble and use. Patience is important to reduce the amount of debugging youíll need to go through in the likely event that problems arise.

The ARP studs were another easy choice, being the most widely used and reasonably priced. The head gasket was replaced not too long ago, so I trusted it and didnít want to go through the additional hassle of pulling the head to install the studs. Iíve heard of several people using the stock gasket without issues, so this was what I decided to go with. I loosened off all the stock bolts gradually and evenly, and then pulled them one by one and replaced them with the studs, then followed the torque spec for installation.
ARP studs:

Beginning of the turbo manifold adapter. I bought an extra set of stock manifolds so I could use two of the same (seemed to be easier plumbing). The material is SCH40 mild steel (heavy as hell). I made all of the flanges myself to help minimize costs. The manifold only required a total of 4 bends and some straight section. Itís a fully divided manifold to mate up to the T3 flange I made.

Some of the exhaust piping. 3” mandrel-bent, and it’s galvanized (for corrosion protection). It’s easy to weld, but you just need to be careful of the galvanized coating (inhaling the fumes can make you really sick).

Pressure testing the manifold (up to 30psi). Aluminum plates with rubber gaskets to seal it off. Used a quick-disconnect air fitting to plumb into the shop’s air supply, and also mounted a pressure gauge to see if it leaks. Divided wastegate plumbing installed:

Rest of exhaust. It was tucked as close to the body as possible for ground clearance purposes. I used all of the stock mounting points for hanging it, and had it run down the centerline of the car to use the existing heat-shielding. Very simple and I’m very pleased with how it turned out.

Intercooler and oil cooler mounted. I used a simple 3/4” square tube for support. The oil cooler is also mounted to tabs on this tube. The IC is supported at the bottom by small tabs welded to the chassis.

TPS and IAT. The TPS is the typical unit from the E36 and others. Part number: 13 63 1 726 591
The IAT is a standard GM unit, bought from DIYautotune. I wanted to mount the IAT as close as possible to the engine, without having to deal with welding into the charge piping. This was an obvious solution. Drill + tap (and also machined it down a bit):

The intake plumbing was fairly straight forward, using a minimal amount of tubes/couplings.
Bought a big, honkin’ 3”-4” adapter for the compressor inlet. Used an existing 3” K&N intake I had lying around for the pre-turbo part of it. Also built a shield around the filter to prevent road debris, but still allow adequate airflow and drainage in the event that water starts pooling there.

The oil system on this car was a bit of a hassle, but I was able to get through it all. I wanted to use the stock oil cooler housing (with thermostat) and not have to deal with relocating it (more plumbing, more mess, more chance for something to leak). I made an inline adapter that goes between the cooler housing and the oil filter. It has ports for the turbo oil feed and an oil pressure sender. I also tapped the housing bolt for an oil temperature sensor.

The unfortunate part about that piece is that the threads on both ends need to be different, which makes life a bit more complicated.
The oil cooler is B&M unit purchased through Summit. When installing the AN-to-NPT fittings onto the cooler you need to use LOTS of Teflon tape. I had to remove the fittings at one point, and the fittings galled the tapped holes in the cooler and stripped out most of the threads. It has been patched with JB weld and is still holding (thankfully).

For removing and installing the oil pan, I needed to lift the engine a bit for clearance issues. I don’t own an engine lift, so I built my own device for lifting the engine. It straddles the engine bay and sits on the frame rails. A large threaded rod with a fastener on one end is attached to the engine lift point at the front, and then it is lifted by turning the nut on the threaded rod. Worked pretty well, although it was still a bit of a pain putting everything back together under there…

I bought some necessary gauges for monitoring the oil system and boost pressure. Oil pressure, oil temperature, and boost. All VDO Vision gauges. There’s also an additional wideband AFR gauge from Innovate. I cut a hole in the center console where the radio and OBC were located (shouldn’t be needing those anymore…), and replaced it with an aluminum sheet with holes for all the gauges.

Mine is bolted to the valve cover with 3 of the studs, and extends over the down pipe and bolts to the turbine outlet flange with 2 rod ends (of opposite thread) to create a turnbuckle system for tensioning.

The final touch on the exhaust system was having all of the manifold components and downpipe ceramic coated. For people in the GTA, my buddy gives good rates for ceramic and powder coating. Company name is Afterburner Performance Coatings. PM me for details….
Bling bling!

How to describe the car: This thing is nuts. (as many of you already experience daily). I’ve never been in something with this much ass-kicking torque before. It’s a new experience and I’m hooked…
The MS tuning is still a work in progress, but it’s coming along reasonably smoothly. The car can spin the wheels on a roll in 2nd, but unfortunately the clutch starts slipping in 3rd (duh….). I can reach full boost (1 bar) by 4500rpm. I’ve got a new Stage 4 clutch in the mail from South Bend and will update when that gets installed. Once my fueling is sorted out, I’ll spend a few hours on a dyno to get the ignition maps finalized (and get some whp numbers!).
Videos will also start showing up once this car is “legal” and insured.
There will also be some updates to this as new things progress (ie. Clutch, new differential, updated cooling system, brakes, etc….)

BMW BMXer

08-06-2009 09:40 PM

Holy shit dude.

Way to keep quiet then come out with the ****ing heat. Nice build.

Bullet Ride

08-06-2009 11:30 PM

Super clean build!
Did you end up staying under $3000?

Axxe

08-06-2009 11:38 PM

Nice build!

ryan_george

08-07-2009 12:21 AM

I didn't want to post an "in-progress" build thread, because sometimes progress was slow.... Figure I could get it all done in one shot.

I didn't make it under my $3000 budget. It was a lot closer to $4000, which isn't bad I suppose.

Insurance has just been sorted out, gotta get the car safetied on Monday, install the new clutch that's waiting for me, and then we're done! (for now...)